Systems and methods for forming metal oxides using metal compounds containing aminosilane ligands

ABSTRACT

A method of forming (and an apparatus for forming) a metal oxide layer on a substrate, particularly a semiconductor substrate or substrate assembly, using a vapor deposition process and one or more precursor compounds that include aminosilane ligands.

FIELD OF THE INVENTION

[0001] This invention relates to methods of forming a metal oxide layeron a substrate using one or more precursor compounds that include one ormore aminosilane ligands during a vapor deposition process. Theprecursor compounds and methods are particularly suitable for theformation of metal oxide layers on semiconductor substrates or substrateassemblies.

BACKGROUND OF THE INVENTION

[0002] The continuous shrinkage of microelectronic devices such ascapacitors and gates over the years has led to a situation where thematerials traditionally used in integrated circuit technology areapproaching their performance limits. Silicon (i.e., doped polysilicon)has generally been the substrate of choice, and silicon dioxide (SiO₂)has frequently been used as the dielectric material with silicon toconstruct microelectronic devices. However, when the SiO₂ layer isthinned to 1 nm (i.e., a thickness of only 4 or 5 molecules), as isdesired in the newest micro devices, the layer no longer effectivelyperforms as an insulator due to the tunneling current running throughit.

[0003] Thus, new high dielectric constant materials are needed to extenddevice performance. Such materials need to demonstrate highpermittivity, barrier height to prevent tunneling, stability in directcontact with silicon, and good interface quality and film morphology.Furthermore, such materials must be compatible with the gate material,electrodes, semiconductor processing temperatures, and operatingconditions.

[0004] High quality thin oxide films of metals, such as ZrO₂, HfO₂,Al₂O₃, and YSZ deposited on semiconductor wafers have recently gainedinterest for use in memories (e.g., dynamic random access memory (DRAM)devices, static random access memory (SRAM) devices, and ferroelectricmemory (FERAM) devices). These materials have high dielectric constantsand therefore are attractive as replacements in memories for SiO₂ wherevery thin layers are required. These metal oxide layers arethermodynamically stable in the presence of silicon, minimizing siliconoxidation upon thermal annealing, and appear to be compatible with metalgate electrodes. Specifically, yttrium and lanthanide oxides have highdielectric constants and can be added as dopants to enhance thedielectric constants of marginal dielectrics like alumina (Al₂O₃).

[0005] This discovery has led to an effort to investigate variousdeposition processes to form layers, especially dielectric layers, basedon metal oxides. Such deposition processes have included vapordeposition, metal thermal oxidation, and high vacuum sputtering. Vapordeposition processes, which includes chemical vapor deposition (CVD) andatomic layer deposition (ALD), are very appealing as they provide forexcellent control of dielectric uniformity and thickness on a substrate.Despite these continual improvements in semiconductor dielectric layers,there remains a need for a vapor deposition process utilizingsufficiently volatile metal precursor compounds that can form a thin,high quality oxide layer, particularly on a semiconductor substrateusing a vapor deposition process.

SUMMARY OF THE INVENTION

[0006] This invention provides methods of forming a metal oxide layer ona substrate, particularly a semiconductor substrate or substrateassembly, using a vapor deposition technique. The methods involveforming the layer by combining one or more metal aminosilane(N(R¹)Si(R²)(R³)(R⁴)) containing precursor compounds with an oxygensource, and optionally with one or more other metal-containing precursorcompounds. The latter precursor compounds, for example, are typicallymetal halides, metal alkyls, metal organo amines, or combinationsthereof.

[0007] The methods of the present invention involve forming a metaloxide layer on a substrate by reacting one or more metal precursorcompounds of the formula M(N(R¹)Si(R²)(R³)(R⁴))₃ (Formula I) with one ormore sources of oxygen (and optionally one or more metal precursorcompounds of a formula different from that of Formula I)). In Formula I:M is a Group IIIA or IIIB metal (preferably, a Group IIIB metal, i.e.,yttrium, scandium, or a lanthanide); and each R¹, R², and R³ isindependently hydrogen or an organic group.

[0008] The resultant oxide layer may include one or more differentmetals (preferably, two metals). In one preferred embodiment, the metaloxide layer is of the formula M₂O₃, optionally including silicon.

[0009] In one embodiment, the present invention provides a method offorming a metal oxide layer on a substrate (e.g., as in a process ofmanufacturing a semiconductor structure). The method includes: providinga substrate (e.g., semiconductor substrate or substrate assembly);providing at least one precursor compound of the formulaM(N(R¹)Si(R²)(R³)(R⁴))₃ (Formula I) and at least one source of oxygen;and contacting the at least one precursor compound with the at least onesource of oxygen to form a metal oxide layer on the substrate (e.g., oneor more surfaces of the semiconductor substrate or substrate assembly)using a vapor deposition process.

[0010] In another embodiment, the present invention provides a method offorming a metal oxide layer on a substrate (e.g., as in a process ofmanufacturing a semiconductor structure). The method includes: providinga substrate (e.g., a semiconductor substrate or substrate assembly)within a deposition chamber; providing a vapor that includes at leastone precursor compound of the formula M(N(R¹)Si(R²)(R³)(R⁴))₃ (FormulaI); providing a vapor that includes at least one source of oxygen; anddirecting the vapors to the substrate to form a metal oxide layer (e.g.,dielectric layer) on one or more surfaces of the substrate.

[0011] In yet another embodiment, the present invention provides amethod of manufacturing a memory device structure. The method includes:providing a substrate having a first electrode thereon; providing avapor that includes at least one precursor compound of the formulaM(N(R¹)Si(R²)(R³)(R⁴))₃ (Formula I); providing a vapor that includes atleast one source of oxygen; and directing the vapors to the substrate toform a metal oxide dielectric layer on the first electrode of thesubstrate; and forming a second electrode on the dielectric layer.

[0012] The methods of the present invention can utilize a chemical vapordeposition (CVD) process, which can be pulsed, or an atomic layerdeposition (ALD) process (a self-limiting vapor deposition process thatincludes a plurality of deposition cycles, typically with purgingbetween the cycles). Preferably, the methods of the present inventionuse ALD. For certain ALD processes, the precursor compounds can bealternately introduced into a deposition chamber during each depositioncycle.

[0013] The present invention also provides a vapor deposition apparatusthat includes: a vapor deposition chamber having a substrate positionedtherein; one or more vessels that include one or more precursorcompounds having the formula M(N(R¹)Si(R²)(R³)(R⁴))₃ (Formula I); andone or more vessels that include one or more sources of oxygen.

[0014] “Semiconductor substrate” or “substrate assembly” as used hereinrefers to a semiconductor substrate such as a base semiconductor layeror a semiconductor substrate having one or more layers, structures, orregions formed thereon. A base semiconductor layer is typically thelowest layer of silicon material on a wafer or a silicon layer depositedon another material, such as silicon on sapphire. When reference is madeto a substrate assembly, various process steps may have been previouslyused to form or define regions, junctions, various structures orfeatures, and openings such as capacitor plates or barriers forcapacitors.

[0015] “Layer” as used herein refers to any metal-containing layer thatcan be formed on a substrate from the precursor compounds of thisinvention using a vapor deposition process. The term “layer” is meant toinclude layers specific to the semiconductor industry, such as “barrierlayer,” “dielectric layer,” and “conductive layer.” (The term “layer” issynonymous with the term “film” frequently used in the semiconductorindustry.) The term “layer” is also meant to include layers found intechnology outside of semiconductor technology, such as coatings onglass.

[0016] “Deposition process” and “vapor deposition process” as usedherein refer to a process in which a metal-containing layer is formed onone or more surfaces of a substrate (e.g., a doped polysilicon wafer)from vaporized precursor compound(s). Specifically, one or more metalprecursor compounds are vaporized and directed to one or more surfacesof a heated substrate (e.g., semiconductor substrate or substrateassembly) placed in a deposition chamber. These precursor compounds form(e.g., by reacting or decomposing) a non-volatile, thin, uniform,metal-containing layer on the surface(s) of the substrate. For thepurposes of this invention, the term “vapor deposition process” is meantto include both chemical vapor deposition processes (including pulsedchemical vapor deposition processes) and atomic layer depositionprocesses.

[0017] “Chemical vapor deposition” (CVD) as used herein refers to avapor deposition process wherein the desired layer is deposited on thesubstrate from vaporized metal precursor compounds (and any reactiongases used) within a deposition chamber with no effort made to separatethe reaction components. In contrast to a “simple” CVD process thatinvolves the substantial simultaneous use of the precursor compounds andany reaction gases, “pulsed” CVD alternately pulses these materials intothe deposition chamber, but does not rigorously avoid intermixing of theprecursor and reaction gas streams, as is typically done in atomic layerdeposition or ALD (discussed in greater detail below).

[0018] “Atomic layer deposition” (ALD) as used herein refers to a vapordeposition process in which numerous consecutive deposition cycles areconducted in a deposition chamber. Typically, during each cycle themetal precursor is chemisorbed to the substrate surface; excessprecursor is purged out; a subsequent precursor and/or reaction gas isintroduced to react with the chemisorbed layer; and excess reaction gas(if used) and by-products are removed. As compared to the one cyclechemical vapor deposition (CVD) process, the longer duration multi-cycleALD process allows for improved control of layer thickness byself-limiting layer growth and minimizing detrimental gas phasereactions by separation of the reaction components. The term “atomiclayer deposition” as used herein is also meant to include the relatedterms “atomic layer epitaxy” (ALE), molecular beam epitaxy (MBE), gassource MBE, organometallic MBE, and chemical beam epitaxy when performedwith alternating pulses of precursor compound(s), reaction gas(es), andpurge (i.e., inert carrier) gas.

[0019] “Chemisorption” as used herein refers to the chemical adsorptionof vaporized reactive precursor compounds on the surface of a substrate.The adsorbed species are irreversibly bound to the substrate surface asa result of relatively strong binding forces characterized by highadsorption energies (e.g., >30 kcal/mol), comparable in strength toordinary chemical bonds. The chemisorbed species typically form amononolayer on the substrate surface. (See “The Condensed ChemicalDictionary”, 10th edition, revised by G. G. Hawley, published by VanNostrand Reinhold Co., New York, 225 (1981)). The technique of ALD isbased on the principle of the formation of a saturated monolayer ofreactive precursor molecules by chemisorption. In ALD one or moreappropriate precursor compounds or reaction gases are alternatelyintroduced (e.g., pulsed) into a deposition chamber and chemisorbed ontothe surfaces of a substrate. Each sequential introduction of a reactivecompound (e.g., one or more precursor compounds and one or more reactiongases) is typically separated by an inert carrier gas purge. Eachprecursor compound co-reaction adds a new atomic layer to previouslydeposited layers to form a cumulative solid layer. The cycle isrepeated, typically for several hundred times, to gradually form thedesired layer thickness. It should be understood that ALD canalternately utilize one precursor compound, which is chemisorbed, andone reaction gas, which reacts with the chemisorbed species.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIGS. 1-3 are exemplary capacitor constructions.

[0021]FIG. 4 is a perspective view of a vapor deposition coating systemsuitable for use in the method of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

[0022] The present invention provides methods of forming a metal oxidelayer (preferably, a mixed metal oxide layer) on a substrate(preferably, a semiconductor substrate or substrate assembly). Themethods of the present invention involve forming a metal oxide layer ona substrate by combining one or more metal precursor compounds theformula M(N(R¹)Si(R²)(R³)(R⁴))₃ (Formula I) with one or more sources ofoxygen, and optionally one or more metal precursor compounds of aformula other than Formula I. In Formula I: M is a Group IIIA or GroupIIIB metal (preferably a Group IIIB metal, i.e., yttrium, scandium, or alanthanide (La, Ce, Pr, Nd, etc.)); and each R¹, R², and R³ isindependently hydrogen or an organic group.

[0023] The metal oxide layer may include one or more different metalsand is preferably of the formula M₂O₃. Optionally, the metal oxide layermay also include silicon, which comes from the precursor of Formula I.

[0024] For embodiments in which there are more than one metal, thedifferent metals may be provided by compounds of Formula I or compoundsother than those of Formula I, such as those disclosed in Applicant'sAssignee's copending applications U.S. Ser. No. _______, filed _______,entitled SYSTEMS AND METHODS FOR FORMING METAL OXIDES USING METALDIKETONATES AND/OR KETOIMINES (Attorney Docket No. 150.01340101) andU.S. Ser. No. _______, filed _______, entitled SYSTEMS AND METHODS FORFORMING METAL-DOPED ALUMINA (Attorney Docket No. 150.01310101).

[0025] The substrate on which the metal oxide layer is formed ispreferably a semiconductor substrate or substrate assembly. Any suitablesemiconductor material is contemplated, such as for example,conductively doped polysilicon (for this invention simply referred to as“silicon”). A substrate assembly may also contain a layer that includesplatinum, iridium, rhodium, ruthenium, ruthenium oxide, titaniumnitride, tantalum nitride, tantalum-silicon-nitride, silicon dioxide,aluminum, gallium arsenide, glass, etc., and other existing orto-be-developed materials used in semiconductor constructions, such asdynamic random access memory (DRAM) devices and static random accessmemory (SRAM) devices, for example.

[0026] Substrates other than semiconductor substrates or substrateassemblies can be used in methods of the present invention. Theseinclude, for example, fibers, wires, etc. If the substrate is asemiconductor substrate or substrate assembly, the layers can be formeddirectly on the lowest semiconductor surface of the substrate, or theycan be formed on any of a variety of the layers (i.e., surfaces) as in apatterned wafer, for example.

[0027] The precursor compounds useful in this invention are of theformula M(N(R¹)Si(R²)(R³)(R⁴))₃ (Formula I), wherein each R can be anorganic group (as described in greater detail below).

[0028] As used herein, the term “organic group” is used for the purposeof this invention to mean a hydrocarbon group that is classified as analiphatic group, cyclic group, or combination of aliphatic and cyclicgroups (e.g., alkaryl and aralkyl groups). In the context of the presentinvention, suitable organic groups for precursor compounds of thisinvention are those that do not interfere with the formation of a metaloxide layer using vapor deposition techniques. In the context of thepresent invention, the term “aliphatic group” means a saturated orunsaturated linear or branched hydrocarbon group. This term is used toencompass alkyl, alkenyl, and alkynyl groups, for example. The term“alkyl group” means a saturated linear or branched monovalenthydrocarbon group including, for example, methyl, ethyl, n-propyl,isopropyl, t-butyl, amyl, heptyl, and the like. The term “alkenyl group”means an unsaturated, linear or branched monovalent hydrocarbon groupwith one or more olefinically unsaturated groups (i.e., carbon-carbondouble bonds), such as a vinyl group. The term “alkynyl group” means anunsaturated, linear or branched monovalent hydrocarbon group with one ormore carbon-carbon triple bonds. The term “cyclic group” means a closedring hydrocarbon group that is classified as an alicyclic group,aromatic group, or heterocyclic group. The term “alicyclic group” meansa cyclic hydrocarbon group having properties resembling those ofaliphatic groups. The term “aromatic group” or “aryl group” means amono- or polynuclear aromatic hydrocarbon group. The term “heterocyclicgroup” means a closed ring hydrocarbon in which one or more of the atomsin the ring is an element other than carbon (e.g., nitrogen, oxygen,sulfur, etc.).

[0029] As a means of simplifying the discussion and the recitation ofcertain terminology used throughout this application, the terms “group”and “moiety” are used to differentiate between chemical species thatallow for substitution or that may be substituted and those that do notso allow for substitution or may not be so substituted. Thus, when theterm “group” is used to describe a chemical substituent, the describedchemical material includes the unsubstituted group and that group withnonperoxidic O, N, S, Si, or F atoms, for example, in the chain as wellas carbonyl groups or other conventional substituents. Where the term“moiety” is used to describe a chemical compound or substituent, only anunsubstituted chemical material is intended to be included. For example,the phrase “alkyl group” is intended to include not only pure open chainsaturated hydrocarbon alkyl substituents, such as methyl, ethyl, propyl,t-butyl, and the like, but also alkyl substituents bearing furthersubstituents known in the art, such as hydroxy, alkoxy, alkylsulfonyl,halogen atoms, cyano, nitro, amino, carboxyl, etc. Thus, “alkyl group”includes ether groups, haloalkyls, nitroalkyls, carboxyalkyls,hydroxyalkyls, sulfoalkyls, etc. On the other hand, the phrase “alkylmoiety” is limited to the inclusion of only pure open chain saturatedhydrocarbon alkyl substituents, such as methyl, ethyl, propyl, t-butyl,and the like.

[0030] In Formula I: M is a metal (including a semimetal or metalloid)selected from Groups IIIA (Al, Ga, In, TI) and IIIB (Y, Sc, and alanthanide) of the Periodic Table. Preferably, M is aluminum, yttrium(Y), scandium (Sc), or a lanthanide (e.g., La, Ce, Pr, Nd, Pm, Sm, Eu,Gd, Tb, Dy, Ho, Er, Tm ,Yb, and Lu). For certain methods of the presentinvention, preferably, M is selected from the group of Y, La, Ce, Pr,Gd, Er, and mixtures thereof.

[0031] In Formula I, R¹, R², R³, and R⁴ are each hydrogen or an organicgroup. Preferably, each of the organic groups of R¹, R², R³, and R⁴contain 1-10 carbon atoms, more preferably, 1-6 carbon atoms, and mostpreferably, 1-4 carbon atoms. Preferably, at least one of the R groupson the silicon (R², R³, or R⁴) is hydrogen and at least one is anorganic group. More preferably, at least one of R², R³, or R⁴ ishydrogen. Preferably, R¹ is an organic group.

[0032] In Formula I, each organic group can optionally containing one ormore heteroatoms (e.g., oxygen or nitrogen), fluorine atoms, orfunctional groups (e.g., a carbonyl group, a hydroxycarbyl group, or anaminocarbyl group). That is, included within the scope of the compoundsof Formula I are compounds wherein at least one ligand includes anorganic group with at least one carbon atom in the organic groupreplaced with one of a carbonyl group, a hydroxycarbyl group, an oxygenatom, a nitrogen atom, or an aminocarbyl group. Also included within thescope of the compounds of Formula I are compounds wherein at least oneligand includes an organic group and at least one hydrogen atom in theorganic group is replaced with a fluorine atom. Most preferably, theorganic groups of Formula I are (C1-C4)alkyl groups, which may be alinear, branched, or cyclic groups, as well as alkenyl groups (e.g.,dienes and trienes), or alkynyl groups. In any of these organic groups,one or more of the hydrogen atoms can be replaced by fluorine atoms. Ofthese, the organic groups are preferably (C1-C4)alkyl moieties.

[0033] Examples of compounds of Formula I include Y(N(tBu)Si(H)(Me)₂)₃,Y(N(tBu)Si(H)(Et)₂)₃, and Er(N(tBu)Si(H)(Me)₂)₃ wherein tBu istert-butyl, Me is methyl, and Et is ethyl.

[0034] Such compounds are relatively low melting, relatively highlyvolatile, and relatively reactive with substrate surfaces.

[0035] The complexes of the present invention can be prepared by avariety of methods known to one of skill in the art. For example,complexes of Formula I can be prepared by reacting metal halides withthe lithium salts of silylamines.

[0036] Various precursor compounds can be used in various combinations,optionally with one or more organic solvents (particularly for CVDprocesses), to form a precursor composition. The precursor compounds maybe liquids or solids at room temperature (preferably, they are liquidsat the vaporization temperature). Typically, they are liquidssufficiently volatile to be employed using known vapor depositiontechniques. However, as solids they may also be sufficiently volatilethat they can be vaporized or sublimed from the solid state using knownvapor deposition techniques. If they are less volatile solids, they arepreferably sufficiently soluble in an organic solvent or have meltingpoints below their decomposition temperatures such that they can be usedin flash vaporization, bubbling, microdroplet formation techniques, etc.Herein, vaporized precursor compounds may be used either alone oroptionally with vaporized molecules of other precursor compounds oroptionally with vaporized solvent molecules, if used. As used herein,“liquid” refers to a solution or a neat liquid (a liquid at roomtemperature or a solid at room temperature that melts at an elevatedtemperature). As used herein, “solution” does not require completesolubility of the solid but may allow for some undissolved solid, aslong as there is a sufficient amount of the solid delivered by theorganic solvent into the vapor phase for chemical vapor depositionprocessing. If solvent dilution is used in deposition, the total molarconcentration of solvent vapor generated may also be considered as ainert carrier gas.

[0037] The solvents that are suitable for this application (particularlyfor a CVD process) can be one or more of the following: aliphatichydrocarbons or unsaturated hydrocarbons (C3-C20, and preferably C5-C10,cyclic, branched, or linear), aromatic hydrocarbons (C5-C20, andpreferably C5-C10), halogenated hydrocarbons, silylated hydrocarbonssuch as alkylsilanes, alkylsilicates, ethers, polyethers, thioethers,esters, lactones, ammonia, amides, amines (aliphatic or aromatic,primary, secondary, or tertiary), polyamines, nitrites, cyanates,isocyanates, thiocyanates, silicone oils, alcohols, or compoundscontaining combinations of any of the above or mixtures of one or moreof the above. The compounds are also generally compatible with eachother, so that mixtures of variable quantities of the precursorcompounds will not interact to significantly change their physicalproperties.

[0038] The precursor compounds can be vaporized in the presence of aninert carrier gas if desired. Additionally, an inert carrier gas can beused in purging steps in an ALD process. The inert carrier gas istypically selected from the group consisting of nitrogen, helium, argon,and combinations thereof. In the context of the present invention, aninert carrier gas is one that does not interfere with the formation ofthe metal-containing layer.

[0039] The vapor deposition processes of the present invention alsoprovide one or more sources of oxygen. Typically, this is in the form oran oxidizing reaction gas. Examples include O₂, O₃, H₂O, N₂O, H₂O₂, SO₂,SO₃, and alcohols (e.g., isopropanol) can be used if desired. Sources ofoxygen can also include metal-containing compounds, such as metalalkoxides, metal oxo alkoxides, and the keto-containing compoundsdisclosed in Applicant's Assignee's copending applications U.S. Ser. No._______, filed _______, entitled SYSTEMS AND METHODS FOR FORMING METALOXIDES USING METAL DIKETONATES AND/OR KETOIMINES (Attorney Docket No.150.01340101) and U.S. Ser. No. _______, filed _______, entitled SYSTEMSAND METHODS FOR FORMING METAL-DOPED ALUMINA (Attorney Docket No.150.01310101).

[0040] The deposition process for this invention is a vapor depositionprocess. Vapor deposition processes are generally favored in thesemiconductor industry due to the process capability to quickly providehighly conformal layers even within deep contacts and other openings.Chemical vapor deposition (CVD) and atomic layer deposition (ALD) aretwo vapor deposition processes often employed to form thin, continuous,uniform, metal-containing (preferably dielectric) layers ontosemiconductor substrates. Using either vapor deposition process,typically one or more precursor compounds are vaporized in a depositionchamber and optionally combined with one or more reaction gases to forma metal-containing layer onto a substrate. It will be readily apparentto one skilled in the art that the vapor deposition process may beenhanced by employing various related techniques such as plasmaassistance, photo assistance, laser assistance, as well as othertechniques.

[0041] The final layer (preferably, a dielectric layer) formedpreferably has a thickness in the range of about 10 Å to about 500 Å.More preferably, the thickness of the metal-containing layer is in therange of about 30 Å to about 80 Å.

[0042] Chemical vapor deposition (CVD) has been extensively used for thepreparation of metal-containing layers, such as dielectric layers, insemiconductor processing because of its ability to provide highlyconformal and high quality dielectric layers at relatively fastprocessing times. The desired precursor compounds are vaporized and thenintroduced into a deposition chamber containing a heated substrate withoptional reaction gases and/or inert carrier gases. In a typical CVDprocess, vaporized precursors are contacted with reaction gas(es) at thesubstrate surface to form a layer (e.g., dielectric layer). The singledeposition cycle is allowed to continue until the desired thickness ofthe layer is achieved.

[0043] Typical CVD processes generally employ precursor compounds invaporization chambers that are separated from the process chamberwherein the deposition surface or wafer is located. For example, liquidprecursor compounds are typically placed in bubblers and heated to atemperature at which they vaporize, and the vaporized liquid precursorcompound is then transported by an inert carrier gas passing over thebubbler or through the liquid precursor compound. The vapors are thenswept through a gas line to the deposition chamber for depositing alayer on substrate surface(s) therein. Many techniques have beendeveloped to precisely control this process. For example, the amount ofprecursor material transported to the deposition chamber can beprecisely controlled by the temperature of the reservoir containing theprecursor compound and by the flow of an inert carrier gas bubbledthrough or passed over the reservoir.

[0044] Preferred embodiments of the precursor compounds described hereinare particularly suitable for chemical vapor deposition (CVD). Thedeposition temperature at the substrate surface is preferably held at atemperature in a range of about 100° C. to about 600° C., morepreferably in the range of about 200° C. to about 500° C. The depositionchamber pressure is preferably maintained at a deposition pressure ofabout 0.1 torr to about 10 torr. The partial pressure of precursorcompounds in the inert carrier gas is preferably about 0.001 torr toabout 10 torr.

[0045] Several modifications of the CVD process and chambers arepossible, for example, using atmospheric pressure chemical vapordeposition, low pressure chemical vapor deposition (LPCVD), plasmaenhanced chemical vapor deposition (PECVD), hot wall or cold wallreactors or any other chemical vapor deposition technique. Furthermore,pulsed CVD can be used, which is similar to ALD (discussed in greaterdetail below) but does not rigorously avoid intermixing of percursor andreactant gas streams. Also, for pulsed CVD, the deposition thickness isdependent on the exposure time, as opposed to ALD, which isself-limiting (discussed in greater detail below).

[0046] A typical CVD process may be carried out in a chemical vapordeposition reactor, such as a deposition chamber available under thetrade designation of 7000 from Genus, Inc. (Sunnyvale, Calif.), adeposition chamber available under the trade designation of 5000 fromApplied Materials, Inc. (Santa Clara, Calif.), or a deposition chamberavailable under the trade designation of Prism from Novelus, Inc. (SanJose, Calif.). However, any deposition chamber suitable for performingCVD may be used.

[0047] Alternatively, and preferably, the vapor deposition processemployed in the methods of the present invention is a multi-cycle ALDprocess. Such a process is advantageous (particularly over a CVDprocess) in that in provides for optimum control of atomic-levelthickness and uniformity to the deposited layer (e.g., dielectric layer)and to expose the metal precursor compounds to lower volatilization andreaction temperatures to minimize degradation. Typically, in an ALDprocess, each reactant is pulsed sequentially onto a suitable substrate,typically at deposition temperatures of about 25° C. to about 400° C.(preferably about 150° C. to about 300° C.), which is generally lowerthan presently used in CVD processes. Under such conditions the filmgrowth is typically self-limiting (i.e., when the reactive sites on asurface are used up in an ALD process, the deposition generally stops),insuring not only excellent conformality but also good large areauniformity plus simple and accurate thickness control. Due to alternatedosing of the precursor compounds and/or reaction gases, detrimentalvapor-phase reactions are inherently eliminated, in contrast to the CVDprocess that is carried out by continuous coreaction of the precursorsand/or reaction gases. (See Vehkamäki et al, “Growth of SrTiO₃ andBaTiO₃ Thin Films by Atomic Layer Deposition,” Electrochemical andSolid-State Letters, 2(10):504-506 (1999)).

[0048] A typical ALD process includes exposing an initial substrate to afirst chemical species (e.g., a metal precursor compound) to accomplishchemisorption of the species onto the substrate. Theoretically, thechemisorption forms a monolayer that is uniformly one atom or moleculethick on the entire exposed initial substrate. In other words, asaturated monolayer. Practically, chemisorption might not occur on allportions of the substrate. Nevertheless, such an imperfect monolayer isstill a monolayer in the context of the present invention. In manyapplications, merely a substantially saturated monolayer may besuitable. A substantially saturated monolayer is one that will stillyield a deposited layer exhibiting the quality and/or properties desiredfor such layer.

[0049] The first species is purged from over the substrate and a secondchemical species (e.g., a different precursor compound) is provided toreact with the first monolayer of the first species. The second speciesis then purged and the steps are repeated with exposure of the secondspecies monolayer to the first species. In some cases, the twomonolayers may be of the same species. As an option, the second speciescan react with the first species, but not chemisorb additional materialthereto. That is, the second species can cleave some portion of thechemisorbed first species, altering such monolayer without forminganother monolayer thereon. Also, a third species or more may besuccessively chemisorbed (or reacted) and purged just as described forthe first and second species. Optionally, the second species (or thirdor subsequent) can include at least one reaction gas if desired.

[0050] Purging may involve a variety of techniques including, but notlimited to, contacting the substrate and/or monolayer with a carrier gasand/or lowering pressure to below the deposition pressure to reduce theconcentration of a species contacting the substrate and/or chemisorbedspecies. Examples of carrier gases include N₂, Ar, He, etc. Purging mayinstead include contacting the substrate and/or monolayer with anysubstance that allows chemisorption by-products to desorb and reducesthe concentration of a contacting species preparatory to introducinganother species. The contacting species may be reduced to some suitableconcentration or partial pressure known to those skilled in the artbased on the specifications for the product of a particular depositionprocess.

[0051] ALD is often described as a self-limiting process, in that afinite number of sites exist on a substrate to which the first speciesmay form chemical bonds. The second species might only bond to the firstspecies and thus may also be self-limiting. Once all of the finitenumber of sites on a substrate are bonded with a first species, thefirst species will often not bond to other of the first species alreadybonded with the substrate. However, process conditions can be varied inALD to promote such bonding and render ALD not self-limiting.Accordingly, ALD may also encompass a species forming other than onemonolayer at a time by stacking of a species, forming a layer more thanone atom or molecule thick.

[0052] The described method indicates the “substantial absence” of thesecond precursor (i.e., second species) during chemisorption of thefirst precursor since insignificant amounts of the second precursormight be present. According to the knowledge and the preferences ofthose with ordinary skill in the art, a determination can be made as tothe tolerable amount of second precursor and process conditions selectedto achieve the substantial absence of the second precursor.

[0053] Thus, during the ALD process, numerous consecutive depositioncycles are conducted in the deposition chamber, each cycle depositing avery thin metal-containing layer (usually less than one monolayer suchthat the growth rate on average is from about 0.2 to about 3.0 Angstromsper cycle), until a layer of the desired thickness is built up on thesubstrate of interest. The layer deposition is accomplished byalternately introducing (i.e., by pulsing) precursor compound(s) intothe deposition chamber containing a semiconductor substrate,chemisorbing the precursor compound(s) as a monolayer onto the substratesurfaces, and then reacting the chemisorbed precursor compound(s) withthe other co-reactive precursor compound(s). The pulse duration ofprecursor compound(s) and inert carrier gas(es) is sufficient tosaturate the substrate surface. Typically, the pulse duration is fromabout 0.1 second to about 5 seconds, preferably from about 0.2 second toabout 3 seconds, and more preferably from about 2 seconds to about 3seconds.

[0054] In comparison to the predominantly thermally driven CVD, ALD ispredominantly chemically driven. Accordingly, ALD is often conducted atmuch lower temperatures than CVD. During the ALD process, the substratetemperature is maintained at a temperature sufficiently low to maintainintact bonds between the chemisorbed precursor compound(s) and theunderlying substrate surface and to prevent decomposition of theprecursor compound(s). The temperature is also sufficiently high toavoid condensation of the precursor compounds(s). Typically thesubstrate temperature is kept within the range of about 25° C. to about400° C. (preferably about 150° C. to about 300° C., and more preferablyabout 250° C. to about 300° C.), which is generally lower than presentlyused in CVD processes. Thus, the first species or precursor compound ischemisorbed at this temperature. Surface reaction of the second speciesor precursor compound can occur at substantially the same temperature aschemisorption of the first precursor or, less preferably, at asubstantially different temperature. Clearly, some small variation intemperature, as judged by those of ordinary skill, can occur but stillbe a substantially same temperature by providing a reaction ratestatistically the same as would occur at the temperature of the firstprecursor chemisorption. Chemisorption and subsequent reactions couldinstead occur at exactly the same temperature.

[0055] For a typical ALD process, the pressure inside the depositionchamber is kept at about 10⁻⁴ torr to about 1 torr, preferably about10⁻⁴ torr to about 0.1 torr. Typically, the deposition chamber is purgedwith an inert carrier gas after the vaporized precursor compound(s) havebeen introduced into the chamber and/or reacted for each cycle. Theinert carrier gas(es) can also be introduced with the vaporizedprecursor compound(s) during each cycle.

[0056] The reactivity of a precursor compound can significantlyinfluence the process parameters in ALD. Under typical CVD processconditions, a highly reactive compound may react in the gas phasegenerating particulates, depositing prematurely on undesired surfaces,producing poor films, and/or yielding poor step coverage or otherwiseyielding non-uniform deposition. For at least such reason, a highlyreactive compound might be considered not suitable for CVD. However,some compounds not suitable for CVD are superior ALD precursors. Forexample, if the first precursor is gas phase reactive with the secondprecursor, such a combination of compounds might not be suitable forCVD, although they could be used in ALD. In the CVD context, concernmight also exist regarding sticking coefficients and surface mobility,as known to those skilled in the art, when using highly gas-phasereactive precursors, however, little or no such concern would exist inthe ALD context.

[0057] After layer formation on the substrate, an annealing process canbe optionally performed in situ in the deposition chamber in a nitrogenatmosphere or oxidizing atmosphere. Preferably, the annealingtemperature is within the range of about 400° C. to about 1000° C.Particularly after ALD, the annealing temperature is more preferablyabout 400° C. to about 750° C., and most preferably about 600° C. toabout 700° C. The annealing operation is preferably performed for a timeperiod of about 0.5 minute to about 60 minutes and more preferably for atime period of about 1 minute to about 10 minutes. One skilled in theart will recognize that such temperatures and time periods may vary. Forexample, furnace anneals and rapid thermal annealing may be used, andfurther, such anneals may be performed in one or more annealing steps.

[0058] As stated above, the use of the complexes and methods of formingfilms of the present invention are beneficial for a wide variety of thinfilm applications in semiconductor structures, particularly those usinghigh dielectric materials. For example, such applications include gatedielectrics and capacitors such as planar cells, trench cells (e.g.,double sidewall trench capacitors), stacked cells (e.g., crown, V-cell,delta cell, multi-fingered, or cylindrical container stackedcapacitors), as well as field effect transistor devices.

[0059] A specific example of where a dielectric layer is formedaccording to the present invention is a capacitor construction.Exemplary capacitor constructions are described with reference to FIGS.1-3. Referring to FIG. 1, a semiconductor wafer fragment 10 includes acapacitor construction 25 formed by a method of the present invention.Wafer fragment 10 includes a substrate 12 having a conductive diffusionarea 14 formed therein. Substrate 12 can include, for example,monocrystalline silicon. An insulating layer 16, typicallyborophosphosilicate glass (BPSG), is provided over substrate 12, with acontact opening 18 provided therein to diffusion area 14. A conductivematerial 20 fills contact opening 18, with material 20 and oxide layer18 having been planarized as shown. Material 20 might be any suitableconductive material, such as, for example, tungsten or conductivelydoped polysilicon. Capacitor construction 25 is provided atop layer 16and plug 20, and electrically connected to node 14 through plug 20.

[0060] Capacitor construction 25 includes a first capacitor electrode26, which has been provided and patterned over node 20. Exemplarymaterials include conductively doped polysilicon, Pt, Ir, Rh, Ru, RuO₂,IrO₂, RhO₂. A capacitor dielectric layer 28 is provided over firstcapacitor electrode 26. The materials of the present invention can beused to form the capacitor dielectric layer 28. Preferably, if firstcapacitor electrode 26 includes polysilicon, a surface of thepolysilicon is cleaned by an in situ HF dip prior to deposition of thedielectric material. An exemplary thickness for layer 28 in accordancewith 256 Mb integration is 100 Angstroms.

[0061] A diffusion barrier layer 30 is provided over dielectric layer28. Diffusion barrier layer 30 includes conductive materials such asTiN, TaN, metal silicide, or metal silicide-nitride, and can be providedby CVD, for example, using conditions well known to those of skill inthe art. After formation of barrier layer 30, a second capacitorelectrode 32 is formed over barrier layer 30 to complete construction ofcapacitor 25. Second capacitor electrode 32 can include constructionssimilar to those discussed above regarding the first capacitor electrode26, and can accordingly include, for example, conductively dopedpolysilicon. Diffusion barrier layer 30 preferably prevents components(e.g., oxygen) from diffusing from dielectric material 28 into electrode32. If, for example, oxygen diffuses into a silicon-containing electrode32, it can undesirably form SiO₂, which will significantly reduce thecapacitance of capacitor 25. Diffusion barrier layer 30 can also preventdiffusion of silicon from metal electrode 32 to dielectric layer 28.

[0062]FIG. 2 illustrates an alternative embodiment of a capacitorconstruction. Like numerals from FIG. 1 have been utilized whereappropriate, with differences indicated by the suffix “a”. Waferfragment 10 a includes a capacitor construction 25 a differing from theconstruction 25 of FIG. 2 in provision of a barrier layer 30 a betweenfirst electrode 26 and dielectric layer 28, rather than betweendielectric layer 28 and second capacitor electrode 32. Barrier layer 30a can include constructions identical to those discussed above withreference to FIG. 1.

[0063]FIG. 3 illustrates yet another alternative embodiment of acapacitor construction. Like numerals from FIG. 1 are utilized whereappropriate, with differences being indicated by the suffix “b” or bydifferent numerals. Wafer fragment 10 b includes a capacitorconstruction 25 b having the first and second capacitor plate 26 and 32,respectively, of the first described embodiment. However, wafer fragment10 b differs from wafer fragment 10 of FIG. 2 in that wafer fragment 10b includes a second barrier layer 40 in addition to the barrier layer30. Barrier layer 40 is provided between first capacitor electrode 26and dielectric layer 28, whereas barrier layer 30 is between secondcapacitor electrode 32 and dielectric layer 28. Barrier layer 40 can beformed by methods identical to those discussed above with reference toFIG. 1 for formation of the barrier layer 30.

[0064] In the embodiments of FIGS. 1-3, the barrier layers are shown anddescribed as being distinct layers separate from the capacitorelectrodes. It is to be understood, however, that the barrier layers caninclude conductive materials and can accordingly, in such embodiments,be understood to include at least a portion of the capacitor electrodes.In particular embodiments an entirety of a capacitor electrode caninclude conductive barrier layer materials.

[0065] A system that can be used to perform vapor deposition processes(chemical vapor deposition or atomic layer deposition) of the presentinvention is shown in FIG. 4. The system includes an enclosed vapordeposition chamber 10, in which a vacuum may be created using turbo pump112 and backing pump 114. One or more substrates 116 (e.g.,semiconductor substrates or substrate assemblies) are positioned inchamber 110. A constant nominal temperature is established for substrate116, which can vary depending on the process used. Substrate 116 may beheated, for example, by an electrical resistance heater 118 on whichsubstrate 116 is mounted. Other known methods of heating the substratemay also be utilized.

[0066] In this process, precursor compounds 160 (e.g., a refractorymetal precursor compound and an ether) are stored in vessels 162. Theprecursor compounds are vaporized and separately fed along lines 164 and166 to the deposition chamber 110 using, for example, an inert carriergas 168. A reaction gas 170 may be supplied along line 172 as needed.Also, a purge gas 174, which is often the same as the inert carrier gas168, may be supplied along line 176 as needed. As shown, a series ofvalves 180-185 are opened and closed as required.

[0067] The following examples are offered to further illustrate thevarious specific and preferred embodiments and techniques. It should beunderstood, however, that many variations and modifications may be madewhile remaining within the scope of the present invention, so the scopeof the invention is not intended to be limited by the examples. Unlessspecified otherwise, all percentages shown in the examples arepercentages by weight.

EXAMPLE Example 1 Deposition of Y₂O₃ by Atomic Layer Deposition

[0068] A Y₂O₃ film was deposited on a 100 nm PVD Pt bottom electrode byALD using alternate pulses of Y[N(tBu)Si(H)(Me)₂]₃ and water; at asubstrate temperature of 298° C. A 1000 Å film resulted from 750 cycles.Each cycle consisted of a 1s yttrium dose, 5s vacuum pump, 0.75s waterdose, 1s argon purge, 5s vacuum pump. A flat capacitor test structure ofsputtered Pt top electrodes on top of the Y₂O₃ was used to measure theelectrical data. Several of the capacitors had measured dielectricconstants near 30 (0.1-100 kHz) and leakage between 10⁻⁷ and 10⁻⁸ A/cm²at 1 V after 700° C. RTO. XPS analysis revealed that carbon was belowdetection limits after the oxidation anneal but 16 atom % Si remained inthe Y₂O₃ layer.

[0069] The complete disclosures of the patents, patent documents, andpublications cited herein are incorporated by reference in theirentirety as if each were individually incorporated. Variousmodifications and alterations to this invention will become apparent tothose skilled in the art without departing from the scope and spirit ofthis invention. It should be understood that this invention is notintended to be unduly limited by the illustrative embodiments andexamples set forth herein and that such examples and embodiments arepresented by way of example only with the scope of the inventionintended to be limited only by the claims set forth herein as follows.

What is claimed is:
 1. A method of manufacturing a semiconductorstructure, the method comprising: providing a semiconductor substrate orsubstrate assembly; providing at least one precursor compound of theformula M(N(R¹)Si(R²)(R³)(R⁴))₃ (Formula I), wherein: M is a Group IIIAor Group IIIB metal; each R¹, R², R³, and R⁴ is hydrogen or an organicgroup; and providing at least one source of oxygen; and contacting theat least one precursor compound and the at least one source of oxygen toform a metal oxide layer on one or more surfaces of the semiconductorsubstrate or substrate assembly using a vapor deposition process.
 2. Themethod of claim 1 wherein the semiconductor substrate or substrateassembly is a silicon wafer.
 3. The method of claim 1 wherein the metaloxide layer is a dielectric layer.
 4. The method of claim 1 wherein M isselected from the group of aluminum, yttrium, scandium, a lanthanide andmixtures thereof.
 5. The method of claim 4 wherein M is selected fromthe group of Y, La, Ce, Pr, Gd, Er, and mixtures thereof.
 6. The methodof claim 1 wherein the metal oxide layer has a thickness of about 30 Åto about 80 Å.
 7. The method of claim 1 wherein R¹, R², R³, and R⁴ areeach independently organic groups having 1-10 carbon atoms.
 8. Themethod of claim 1 wherein at least one of R², R³, or R⁴ is hydrogen. 9.The method of claim 1 wherein R¹ is a (C1-C4) organic group.
 10. Themethod of claim 1 further comprising providing at least onemetal-containing precursor compound of a formula different than that ofFormula I.
 11. The method of claim 10 wherein the source of oxygen isthe metal-containing precursor compound of a formula different than thatof Formula I.
 12. The method of claim 1 wherein the metal oxidecomprises two different metals.
 13. The method of claim 1 wherein themetal oxide further includes silicon.
 14. A method of manufacturing asemiconductor structure, the method comprising: providing asemiconductor substrate or substrate assembly within a depositionchamber; providing a vapor comprising at least one precursor compound ofthe formula M(N(R¹)Si(R²)(R³)(R⁴))₃ (Formula I), wherein: M is a GroupIIIA or Group IIIB metal; each R¹, R², R³, and R⁴ is hydrogen or anorganic group; and providing a vapor comprising at least one source ofoxygen; and directing the vapors to the semiconductor substrate orsubstrate assembly to form a metal oxide dielectric layer on one or moresurfaces of the semiconductor substrate or substrate assembly.
 15. Themethod of claim 14 wherein the precursor compounds are directed to thesemiconductor substrate or substrate assembly in the presence of aninert carrier gas.
 16. The method of claim 14 wherein M is selected fromthe group of aluminum, yttrium, scandium, a lanthanide and mixturesthereof.
 17. The method of claim 16 wherein M is selected from the groupof Y, La, Ce, Pr, Gd, Er, and mixtures thereof.
 18. The method of claim14 wherein the providing and directing steps are accomplished using achemical vapor deposition process.
 19. The method of claim 18 whereinthe temperature of the semiconductor substrate or substrate assembly isabout 100° C. to about 600° C.
 20. The method of claim 18 wherein thesemiconductor substrate or substrate assembly is in a deposition chamberhaving a pressure of about 0.1 torr to about 10 torr.
 21. The method ofclaim 14 wherein the providing and directing steps are accomplishedusing an atomic layer deposition process comprising a plurality ofdeposition cycles.
 22. The method of claim 21 wherein during the atomiclayer deposition process the metal oxide layer is formed by alternatelyintroducing the vapor comprising at least one precursor compound and thevapor comprising at least one source of oxygen during each depositioncycle.
 23. The method of claim 21 wherein the temperature of thesemiconductor substrate or substrate assembly is about 25° C. to about400° C.
 24. The method of claim 21 wherein the semiconductor substrateor substrate assembly is in a deposition chamber having a pressure ofabout 10⁻⁴ torr to about 1 torr.
 25. The method of claim 14 wherein themetal oxide comprises two different metals.
 26. The method of claim 14further comprising providing a vapor comprising at least onemetal-containing precursor compound of a formula different than that ofFormula I.
 27. The method of claim 26 wherein the source of oxygen isthe metal-containing precursor compound of a formula different than thatof Formula I.
 28. The method of claim 14 wherein the metal oxide layerfurther comprises silicon.
 29. A method of forming a metal oxide layeron a substrate, the method comprising: providing a substrate; providingat least one precursor compound of the formula M(N(R¹)Si(R²)(R³)(R⁴))₃(Formula I), wherein: M is Group IIIA or Group IIIB metal; each R¹, R²,R³, and R⁴ is hydrogen or an organic group; and providing at least onesource of oxygen; and contacting the at least one precursor compound andthe at least one source of oxygen to form a metal oxide layer on thesubstrate using a vapor deposition process.
 30. The method of claim 29wherein M is selected from the group of aluminum, yttrium, scandium, alanthanide, and mixtures thereof.
 31. The method of claim 30 wherein Mis selected from the group of Y, La, Ce, Pr, Gd, Er, and mixturesthereof.
 32. The method of claim 29 wherein the metal oxide layer has athickness of about 30 Å to about 80 Å.
 33. The method of claim 29wherein R¹, R², R³, and R⁴ are each independently organic groups having1-10 carbon atoms.
 34. The method of claim 29 wherein at least one ofR², R³, or R⁴ is hydrogen.
 35. The method of claim 29 wherein R¹ is a(C1-C4) organic group.
 36. The method of claim 29 further comprisingproviding at least one metal-containing precursor compound of a formuladifferent than that of Formula I.
 37. The method of claim 36 wherein thesource of oxygen is the metal-containing precursor compound of a formuladifferent than that of Formula I.
 38. The method of claim 29 wherein themetal oxide comprises two different metals.
 39. The method of claim 29wherein the metal oxide layer further comprises silicon.
 40. A method offorming a metal oxide layer on a substrate, the method comprising:providing a substrate; providing a vapor comprising at least oneprecursor compound of the formula M(N(R¹)Si(R²)(R³)(R⁴))₃ (Formula I),wherein: M is a Group IIIA or a Group IIIB metal; each R¹, R², R³, andR⁴ is hydrogen or an organic group; and providing a vapor comprising atleast one source of oxygen; and directing the vapors to the substrate toform a metal oxide layer on the substrate.
 41. The method of claim 40wherein the providing and directing steps are accomplished using achemical vapor deposition process.
 42. The method of claim 40 whereinthe providing and directing steps are accomplished using an atomic layerdeposition process comprising a plurality of deposition cycles.
 43. Themethod of claim 40 wherein the metal oxide comprises two differentmetals.
 44. A method of manufacturing a memory device structurecomprising: providing a substrate having a first electrode thereon;providing a vapor comprising at least one precursor compound of theformula M(N(R¹)Si(R²)(R³)(R⁴))₃ (Formula I), wherein: M is a Group IIIAor a Group IIIB metal; each R¹, R², R³, and R⁴ is hydrogen or an organicgroup; and providing a vapor comprising at least one source of oxygen;and directing the vapors to the substrate to form a metal oxidedielectric layer on the first electrode of the substrate; and forming asecond electrode on the dielectric layer.
 45. The method of claim 44wherein the providing and directing steps are accomplished using achemical vapor deposition process.
 46. The method of claim 44 whereinthe providing and directing steps are accomplished using an atomic layerdeposition process comprising a plurality of deposition cycles.
 47. Themethod of claim 44 wherein the metal oxide comprises two differentmetals.
 48. A vapor deposition apparatus comprising: a vapor depositionchamber having a substrate positioned therein; one or more vesselscomprising one or more precursor compounds of the formulaM(N(R¹)Si(R²)(R³)(R⁴))₃ (Formula I), wherein: M is a Group IIIA or aGroup IIIB metal; each R¹, R², R³, and R⁴ is hydrogen or an organicgroup; and one or more vessels comprising one or more sources of oxygen.49. The apparatus of claim 48 wherein the substrate is a silicon wafer.50. The apparatus of claim 48 further comprising one or more sources ofan inert carrier gas for transferring at least the one or more precursorcompounds to the vapor deposition chamber.